Zilpha Keatley Snyder has proven herself a nimble-fingered craftswoman before, in "The Egypt Game" and "The Velvet Room," but in "The Truth About Stone Hollow" she never even gets her materials together. There are some wisps and scraps labeled creepy cottage, new boy at school, crippled father, and there are some ghosts blowing around the landscape like plastic bags, but there are so many loose ends in this book you could build a bird's nest out of them.